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本文尝试利用卫星重力观测资料和震后黏弹性松弛理论研究苏门答腊地区的区域流变结构,为更好地认识区域地球动力学环境提供依据.利用GRACE卫星重力资料,计算了2004年苏门答腊Mw9.3地震的同震及震后的重力变化.计算中使用平滑半径为500km的高斯滤波器.结果显示苏门答腊Mw9.3地震破裂东侧以陆地为主的上盘同震下沉量很大,造成约9×10-8ms-2的重力下降阶变,而西侧处于海水下的下盘重力同震上升较小约2×10-8ms-2,但其震后上升较快.流变结构对岩石的变形有很大的影响,是地球动力学数值模拟取得可靠科学结果的基础.本文尝试了利用卫星重力变化时间序列来反演苏门答腊地区的黏滞性结构;即基于GRACE时变重力场,利用自重力、黏弹性、平面分层模型模拟了该地震的同震和震后变形,并将获得的空间固定点的重力变化与GRACE重力场及点位时间序列进行比较,估计该地区的黏滞性系数在1.0×1018Pas的量级,且断层两侧的流变参数存在差异.最后结合苏门答腊区域的构造特点讨论了黏滞性系数的影响因素.
This paper attempts to study the regional rheological structure of Sumatra by using the gravity observation data and post-earthquake viscoelastic relaxation theory to provide a basis for better understanding the regional geodynamic environment.Using GRACE satellite gravity data, the calculation of the Sumatra Mw9.3 Earthquakes and post-earthquake gravity changes.The Gaussian filter with a smooth radius of 500km was used in the calculation.The results show that the terrestrial-based terrestrial plateau mainly on the east side of the Sumatra Mw9.3 earthquake has a large amount of subsidence and causes about 9 × 10-8 ms-2, and the gravity coseismic rise of the lower part of the sea under the sea surface is small by about 2 × 10-8 ms-2, but it increases rapidly after the earthquake. Which is the foundation of reliable scientific results obtained by numerical simulation of geodynamics.This paper attempts to use the time series of satellite gravity to invert the viscous structure of Sumatra region; that is, based on GRACE time-varying gravitational field, The coseismic and post-earthquake deformations of the earthquake are simulated by gravity, viscoelasticity and plane stratification models. The gravitational changes of the obtained fixed points in space are compared with the GRACE gravitational field and the point time series. In the order of 1.0 × 1018Pas, and differences in viscosity of rheological parameters coefficient area on both sides of the fault. Finally, binding region structural characteristics discussed Sumatra factors coefficient of viscosity.